cmos filter

fuzz circuit comparison.

Guitarists love there distorion pedals. Here some simple distortion circuits are shown and analysed what they do to the audio signal.

about

A state variable filter is constructed with two integrator amplifier and a summer. The integrators are low bass filters. The output of both is mixed back to the input. This will give three resonses. A High pass, band pass and low pass response.

2021-11-21T13:18:26.717830 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/
2021-11-21T13:18:26.717830 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/

Figure 1: State variable filter topology

2021-11-21T13:18:26.932979 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/
2021-11-21T13:18:26.932979 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/

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Figure 2: Simulation of a state variable filter with opamps.

integrator

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2021-11-21T13:18:28.211181 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/
2021-11-21T13:18:28.211181 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/

cmos svf

2021-11-21T13:18:28.380172 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/
2021-11-21T13:18:28.380172 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/

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2021-11-21T13:18:28.854589 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/
2021-11-21T13:18:28.854589 image/svg+xml Matplotlib v3.5.0, https://matplotlib.org/

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Figure 3: Overdrive 250 Analysis.

state variable biquad filter

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Figure 3: State Variable biquad filter.

references